Update of messages' `ValidateBasic` and genesis state validation

[niilptr]

This PR:

• updates deposit, withdraw and claim messages' ValidateBasic functions,
• adds unit tests for messages' ValidateBasic and for the genesis state,
• removes ValidateBasic check in cli tx processing functions because redundant (ValidateBasic is called by tx.GenerateOrBroadcastTxCLI())
• removes old unused commented-out code
• groups message files content (of types package) inside a single file (and same for message-test files)

[0xstepit]

Good job